W126 purge valve

[LandYaghtLover]

I assume the purge valve removes fumes from the tank? I am been having issues getting my economy up and adjusting lambda. I get the duty cycle dialed in while the purge line is disconnected. All is well. Then when hooked up, the car acts like it has a vacuum leak. Even after a long idle, etc.

So now I am driving around with the vac line pugged and the car is very different. The engine runs cooler and overall the car is more responsive. And economy is up, I am already over my usual average milage and counting.

Can I leave the line plugged?